I don't really know when the trend started (maybe with Dallas?), but it's many years that cliffhangers are a "thing" of TV series. You reach the season finale, the action gets tense and exciting, and then... FADE OUT, show's over, please come back next year or next September and meamwhile suffer!!!
Do you like cliffhangers, do they piss you off, do you consider them a cop out or you feel there's a reason for them?
I think that writers should make the audience want to come back by writing interesting and compelling stories, getting you interested in the characters, and not by going "If you want to know if your favorte character lives or dies watch the next season premiere". Some cliffhangers I don't mind - Fringe season 2 had an acceptable one, Breaking Bad season 3 had a good cliffhanger that still let you knew what went on, while the just aired cliffhanger of The X Files' revival is Chris Carter trolling for example... also True Blood had irritating cliffhangers, every season finale would resolve the main conflict in the first part, then the middle of the episode would go on meandering, and then final scene for shock value just because they "had" to stick a cliffhanger there.
So... vent your frustations at annoying cliffhangers and applaud intelligent ones here!